Weldability of High Nitrogen Stainless Steel.

Woo, Insu; Kikuchi, Yasushi

doi:10.2355/isijinternational.42.1334

Cited by 99 publications

(46 citation statements)

References 36 publications

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“…These include blowhole generation or nitride precipitation, caused by heat input during the welding process due to the high nitrogen content [1][2][3][4][5][6]. Thus, the application of a solid state joining process for HNS, which can be performed below its melting points, is significantly demanded [7,8].…”

Section: Introductionmentioning

confidence: 99%

The Possibility of Friction Stir Welding of High Nitrogen-containing Austenitic Stainless Steel

Miyano

Fujii

Yangshan

et al. 2010

Int.J.Soc.Mater.Eng.Resour.

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To develop the practical use of high nitrogen-containing austenitic stainless steels (HNS), the possibility of using friction stir welding (FSW) of HNS was examined. In this report, butt-welding of 2 mm thick HNS steel plates was performed using a load-controlled FSW machine. Two types of welding tool materials were used in this study, namely, a Si 3 N 4 -based material and a WC-Co-based material. For FSW with Si 3 N 4 , fullpenetrated and defect-free butt welding joints were successfully produced. On the other hand, for FSW with WC-Co, the tool was deformed and the stir zone did not completely reach the bottom. The stir zone produced by the Si 3 N 4 tool showed a Vicker's hardness higher than the base metal and displayed a fine microstructure due to recrystallization. The yield strength and the tensile strength of the welds produced by the Si 3 N 4 tool exceeded that of the base metal.

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Section: Introductionmentioning

confidence: 99%

The Possibility of Friction Stir Welding of High Nitrogen-containing Austenitic Stainless Steel

Miyano

Fujii

Yangshan

et al. 2010

Int.J.Soc.Mater.Eng.Resour.

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“…The use of such a material may provide comparatively longer life with enhanced safety of any component requiring higher stress for a rapid crack propagation indicating more resistance to brittle fracture. [1][2][3][4][5] The austenitic stainless steel being a readily weldable material, the fabrication of its components and structures in various applications is largely carried out by using different welding processes and procedures. However, the quality of weld joints of this class of steel primarily depends upon thermal behavior of the welding processes employed with or without involvement of fluxes.…”

Section: Introductionmentioning

confidence: 99%

Improvement of Weld Characteristics by Variation in Welding Processes and Parameters in Joining of Thick Wall 304LN Stainless Steel Pipe

2008

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Various properties of weld joints of 25 mm thick wall 325 mm O.D, 304LN austenitic stainless steel pipe prepared by using different welding process and conventional V-groove as per AWS specification have been compared. The welding was carried out by commonly used shielded metal arc welding (SMAW), gas metal arc welding (GMAW) and pulsed current gas metal arc welding (P-GMAW) processes. In P-GMAW process the influence of pulse parameters have been studied by considering their summarized influence defined by a dimensionless hypothetical factor fϭ[(I b /I p )f · t b ] where, t b ϭ[(1/f )Ϫt p ]. The characteristics of weld joints with respect to their metallurgical, mechanical, corrosion and fracture mechanics properties as well as residual stresses have been studied and compared. Welding of thick wall stainless steel pipe by P-GMAW process significantly improves the tensile properties, reduces the inclusion and porosity content, increases initiation fracture toughness and lowers residual stresses of weld joint in comparison to those observed of SMA and GMA weld joints. The influence of f on properties of P-GMA weld joints is primarily attributed to the reduction in severity of weld thermal cycle and refinement of microstructure of weld deposit.KEY WORDS: austenitic stainless steel; SMAW; GMAW; P-GMAW; pulse parameters; residual stresses; inter granular corrosion; microstructure; mechanical properties; fracture toughness. stainless steel requiring multipass weld deposition.In view of the above an effort has been made in the present investigation to carry out a comparative study on the characteristics of conventional V-groove welds of 304LN SS pipe prepared by using shielded metal arc (SMA), GMAW and P-GMAW processes. The P-GMA weld joints have been further compared by considering the influence of pulse parameters in reference to variation in f. The characteristics of weld joint have been analysed primarily with respect to the distribution of longitudinal and transverse residual stresses at the top and root of the weld joints and the microstructure of the weld and HAZ. In order to understand their utility the weld joints are also briefly characterised by studying their mechanical, fracture mechanics and corrosion properties. Experimentation Welding of PipesThe welding of 25 mm thick wall and 325 mm outer diameter AISI 304LN stainless steel pipe has been carried out using GTAW autogenously and in consecutive two root passes followed by filling passes using SMA, GMA and P-GMA welding processes at conventional V-groove confirming the ASME Section IX of Boiler and Pressure Vessel Code. Schematic diagram of the weld groove as well as the consumable root insert used of matching composition with filler metal have been shown in Figs. 1(a) and 1(b) respectively. The multipass welding was performed by using appropriately designed welding procedure specifications (WPS) resulting in a practically sound weld with respect to lack of fusion. The welding was carried out in 1GR position by holding the pipes in a rotating table with t...

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“…Some problems will probably occur in welding of HNS, such as nitrogen loss, nitride, hot cracking and so on. [7][8][9][10][11][12] The nitrogen loss in the weld metal consists of the nitrogen desorption and nitrogen pore. Because high properties are attributed to high nitrogen content, the nitrogen loss in the weld metal will result in the decrease of mechanical properties during welding of HNS.…”

Section: Introductionmentioning

confidence: 99%

“…So Eq. (2) can be modified for HNS as follows;Ni eq ϭNi%ϩ30ϫC%ϩ0.5ϫMn%ϩbϫN% ........ (4) According to the references, 11,25) b is in the range of 13.4 to 30. So the ratio Cr eq /Ni eq is between 0.77 and 1.11 for the high nitrogen steel 1Cr22Mn16N, which means that the solidification mode is the A or AF mode.…”

mentioning

confidence: 99%

Porosity and Nitrogen Content of Weld Metal in Laser Welding of High Nitrogen Austenitic Stainless Steel

2007

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Some problems such as nitrogen desorption and pores always occur in the weld metal during welding of high nitrogen steel. In order to study the nitrogen content and porosity of the weld metal of high nitrogen steel 1Cr22Mn16N, the steel was welded by CO 2 laser welding, and the influence of the shielding gas composition and heat input on the nitrogen content and porosity of the weld metal was investigated. The experimental results indicate that the weld nitrogen content increases slightly with the increase of the nitrogen content in shielding gas under the same laser welding conditions. The nitrogen content of the weld metal decreases with the increase of the heat input when pure argon is used as the shielding gas, whereas that of the weld metal is improved with the increase of the heat input when some nitrogen is added to the shielding gas. The higher the heat input, the less the porosity in the weld metal, and the more nitrogen in the shielding gas, the less the porosity becomes.KEY WORDS: high nitrogen stainless steel; laser welding; nitrogen content; porosity. used to focus the laser beam to the minimum spot of 0.2 mm in diameter, and the focal point was located just on the plate surface. Full-penetration bead-on-plate welding was carried out under four kinds of welding conditions. The laser power is 2.4 kW, and the welding speed is 1.20, 0.80, 0.60 and 0.48 m · min Ϫ1, which the heat input corresponding to is 120, 180, 240 and 300 J · mm Ϫ1, respectively. For each welding condition, five kinds of shielding gas compositions with gas flow rate of 400 L · h Ϫ1 for axial flow are used, in which the nitrogen content (weight percent) is 0, 5 %, 25 %, 50 % and 100 %, respectively. All the Ar-N 2 mixtures were premixed. After welding, the welds were inspected by Xray radiographic examination taken from the top surface to observe the porosity distribution in the weld, and the diameter of pore that can be detected is not less than 0.1 mm. The nitrogen content in the welds was analyzed by an oxygen and nitrogen analyzer, and the location of the sample in the weld used for the nitrogen analysis is shown in Fig. 2. The specimens of the welds for optical observation were mechanically polished and etched with a 10 % oxalic acid solution at 5 V for 30 s. Figure 3 shows the nitrogen content of the welds under different shielding gas compositions. It can be clearly found that the nitrogen content of the welds changes within the range of 0.53-0.59 %, that is similar with the nitrogen content of the base metal. The nitrogen content in the weld increases slightly with the increase of the N 2 in shielding gas under the same heat input. With pure argon as shielding gas, the nitrogen content of the weld is lower than that of the base metal. When the nitrogen content in the shielding gas is more than a critical value, the weld nitrogen content is higher than that of the base metal. The influence of heat input on the weld nitrogen content can be also found from Fig. 3. The nitrogen content in the weld metal decreases with the increa...

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Weldability of High Nitrogen Stainless Steel.

Cited by 99 publications

References 36 publications

The Possibility of Friction Stir Welding of High Nitrogen-containing Austenitic Stainless Steel

The Possibility of Friction Stir Welding of High Nitrogen-containing Austenitic Stainless Steel

Improvement of Weld Characteristics by Variation in Welding Processes and Parameters in Joining of Thick Wall 304LN Stainless Steel Pipe

Porosity and Nitrogen Content of Weld Metal in Laser Welding of High Nitrogen Austenitic Stainless Steel

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